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    <title>Document</title>
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<script>
    //实例化promise对象
    const p = new Promise(function (resolve, reject) {
        setTimeout(() => {
            // let data = "用户数据";
            // //resolve
            // resolve(data)
            let err ="数据读取失败"
            reject(err);
        }, 1000);
    });
    //调用 promise对象的then方法
    p.then(function (value) {
        console.log(value)
    }, function (reason) {
        console.error(reason)
    })
</script>

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